1. Field
The present invention provides a rotational atherectomy device for removing a stenotic lesion from within a vessel of a patient. More specifically, the invention relates to a rotational atherectomy device for removing or reducing stenotic lesions in blood vessels such as a human artery by rotating an abrasive element within the vessel to partially or completely ablate the unwanted material.
2. Description of Related Art
Atherosclerosis, the clogging of arteries, is a leading cause of coronary heart disease. Blood flow through the peripheral arteries (e.g., carotid, femoral, renal, etc.), is similarly affected by the development of atherosclerotic blockages. A conventional method of removing or reducing blockages in blood vessels is known as rotational atherectomy. A long guidewire is advanced into the diseased blood vessel and across the stenotic lesion. A hollow drive shaft is then advanced over the guidewire. The distal end of the drive shaft terminates in a burr provided with an abrasive surface formed from diamond grit or diamond particles. The burr is positioned against the occlusion and the drive shaft rotated at extremely high speeds (e.g., 20,000-160,000 rpm). As the burr rotates, the physician slowly advances it so that the abrasive surface of the burr scrapes against the occluding tissue and disintegrates it, reducing the occlusion and improving the blood flow through the vessel. Such a method and a device for performing the method are described in, for example, U.S. Pat. No. 4,990,134 to Auth. It is also known from U.S. Pat. No. 6,132,444 to Shturman (the instant inventor) et al, to provide a drive shaft with an abrasive element eccentrically positioned proximally to and spaced away from the distal end of the drive shaft.
Rotational angioplasty (atherectomy) is frequently used to remove atherosclerotic or other blocking material from stenotic (blocked) coronary arteries and other blood vessels. However, a disadvantage with this technique is that abraded particles can migrate along the blood vessel distally and block very small diameter vessels including capillaries of the heart muscle itself. The effect of the particulate debris produced by this procedure is of major concern to physicians who practice in this field. Clearly, the existence of particulate matter in the blood stream is undesirable and can cause potentially life-threatening complications, especially if the particles are over a certain size.
Although the potentially detrimental effect caused by the presence of abraded particles in the blood vessels is reduced if they are very small microparticles, it is much more preferable to remove from the treated blood vessel any debris abraded or otherwise released from the stenotic lesion during treatment and thereby prevent migration of debris to other locations along the treated blood vessel.
A rotational atherectomy device, described in U.S. Pat. No. 5,681,336 (to Clement et al), has been proposed which attempts to prevent migration of abraded particles along the blood stream by removing the ablated material from the blood vessel whilst the device is in use. The rotational atherectomy device known from U.S. Pat. No. 5,681,336 (to Clement et al.) has a complicated construction and is difficult to manufacture on a commercial scale.
A number of disadvantages associated with the known rotational atherectomy devices have been addressed in WO 2006/126076, WO 2006/126175 and WO 2006/126176 to Shturman (the instant inventor). The present invention seeks to further improve rotational atherectomy devices known from these documents and other disadvantages associated with known atherectomy devices.
Two most preferred embodiments of the Rotational Atherectomy Device with Solid Support Elements are described in WO 2006/126076. Both embodiments comprise an abrasive element and a pair of solid support elements mounted to a hollow drive shaft formed from a torque transmitting coil and a fluid impermeable membrane. In both preferred embodiments, the abrasive element is located proximal to and spaced away from the distal end. The solid support elements described in WO 2006/126076 are rounded. One of them is located at the distal end of the drive shaft and is referred to as the distal solid support element. The other is located proximal to and spaced away from the abrasive element and is referred to as the proximal distal support element.
In one embodiment of the invention described in WO 2006/126076, the abrasive element has its centre of mass spaced away from the longitudinal or rotational axis of the drive shaft. In that embodiment, both the distal and the proximal solid support elements also have their centres of mass spaced radially away from the longitudinal or rotational axis of the drive shaft, the centre of mass of each of the two solid support elements being located diametrically opposite to the centre of mass of the abrasive element with respect to the longitudinal axis of the drive shaft so that the distal and proximal solid support elements act as counterweights with respect to the abrasive element when the drive shaft rotates. Most preferably, the distal and proximal solid support elements are located in the same longitudinal plane as the centre of mass of the abrasive element, the longitudinal plane extending through the longitudinal or rotational axis of the drive shaft.
In another embodiment described in WO 2006/126076, the abrasive element and the solid support elements have their centres of mass coaxial with the longitudinal or rotational axis of the fluid impermeable drive shaft.
In both embodiments described in WO 2006/126076, pressurised fluid enters treated vessel only through a distal end opening of the fluid impermeable lumen of the drive shaft.